16691
Accession Number
35838
Author
Dai, Shi-bing;Chow, Wing-Keung;Zhu, Shang-you;Zhang, De-bing
Title Of Article Chaper
Non-destructive desalination of historic fair-faced brick façade and effectiveness control – an example of the restoration work at PB 570 Cattle Depot Artists Village, Hong Kong
Title Of Journal Book
Sciences of Conservation and Archaeology
Volume
25
Issue
2
Pages
52-58
Collation
7 p. : ills.
Reference Bibliography
Includes bibliographic references
ISSN
1005-1538
Language Of Text
Chinese
Language Of Summary
Chinese;English
Literature Type
Serial
Literature Level
Analytic
Abstract
The fair - faced brick facade is one of the most important finishes found in contemporary historic buildings in China. Unlike most monuments or historic sites, those buildings are still utilized or need to be restored to provide new functions. However, almost all fair - faced brick facades are moderately to highly contaminated with water - soluble salts, which may come from rising dampness , air - home pollution , wrong repair materials (like cement) or the historical materials themselves due to chemical weathering. The traditional method in China to deal with such salt - contaminated brick stones has been to replace all of them with new stones. However, recently more effort has been made to nondestructively removing those salts in order to reuse them to meet the international guidelines for heritage conservation, and also because of ecological considerations. One of the effective methods for removing water-soluble salts is the so called poulticing . To understand the nature of salt contamination and the effectiveness of such poulticing technologies under sub - tropical climate, studies were carried out at PB570, Cattle Depot Artists Village, 63 Mu Tau Kok Road, To Kwa Wan, Hong Kong, which is undergoing restoration. Water-soluble salts on bricks before and after desalination, dry poultices of each desalination procedure were analyzed with the help of ion chromatography. The applied poultice was a mixture of cellulose, clay minerals and minor amounts of additives, but no organic or inorganic binders. The Cl - , N03- , SO24- , contents of dust samples before desalination fall into then high range category according to WTA Code of Practice 4 5-99/D. After three desalination procedures, the concentration of all salts of bricks fell into the low range. These results demonstrate that a specially formulated poultice based on cellulose and clays can effectively remove most water - soluble salts. Restoration of the entire facade includes dentist repairing, rebuilding, reprofiling, repointing with NHL - mortar, impregnation with water repellants, and reinstallation of the rising dump barrier with the help of chemical injection.
Keywords
brick;façade;building;desalination;poultice;water;soluble;salt;restoration
pub_id
16691